1. Field of the Invention
The present invention relates to a semiconductor device made of a group III nitride semiconductor (sometimes referred to simply as a “nitride semiconductor” below) and a manufacturing method therefor.
2. Description of Related Art
A group III nitride semiconductor is a semiconductor that uses nitrogen as the group V element in a group III-V semiconductor. Aluminum nitride (AlN), gallium nitride (GaN), and indium nitride (InN) are representative examples thereof. In general, it is possible to express this as AlXInYGa1-X-YN (0≦X≦1, 0≦Y≦1, 0<X+Y<1).
A MISFET (metal-insulator-semiconductor field effect transistor) using such a nitride semiconductor is proposed. Patent Document 1 discloses one example of such a MISFET. The MISFET disclosed in Patent Document 1 has a layered configuration including a GaN layer and an AlGaN layer, and an interlayer insulating layer is formed on the AlGaN layer. The interlayer insulating layer has an opening that exposes the surface of the AlGaN layer, and a gate insulating layer is disposed in this opening. A gate electrode is formed on the gate insulating layer. The gate insulating layer has a multilayer structure including an Al2O3 film and an SiO2 film.